Preparation method of concentration gradient rare earth element doped WC particle reinforced iron-based composite material

Abstract

The present invention discloses a method for preparing a concentration-gradient rare earth element-doped WC particle-reinforced iron-based composite material, which belongs to the technical field of wear-resistant and corrosion-resistant material preparation. The composite layer of the composite material of the present invention is divided into a matrix, a reinforcement and a metal powder; wherein the reinforcement is a mixture of tungsten carbide particles with different concentrations of rare earth elements attached to the surface in sequence and pure iron powder. The preparation method is to mix the rare earth elements with a concentration gradient with the tungsten carbide particles through a binder, and perform ball milling to make the rare earth elements uniformly distributed on the surface of the tungsten carbide particles. The obtained reinforcement powder is ball milled again with pure iron powder, mixed powder is pressed into tablets, and vacuum sintered to obtain a concentration-gradient rare earth element-doped WC particle-reinforced iron-based composite material. The mechanical properties of the concentration-gradient rare earth element-doped WC particle-reinforced iron-based composite material prepared by the present invention are significantly improved, the hardness and wear resistance are improved, and the interface problem is also improved.

Description

Technical Field

[0001] The invention relates to a method for preparing a concentration-gradient rare earth element-doped WC particle-reinforced iron-based composite material, belonging to the technical field of preparation of wear-resistant and corrosion-resistant composite materials. Background Art

[0002] With the development of modern industry, the application of wear-resistant materials under special working conditions is becoming more and more extensive. However, during service, a single type of metal or metal alloy is difficult to meet the modern industry's requirements for material wear resistance, and it is difficult to adapt to high-speed and high-impact working environments. After being worn by hard materials, they will quickly fail, and production efficiency will be significantly reduced, resulting in a large amount of material waste. Therefore, ceramic particle-reinforced iron-based composites with adjustable structure and organization need to be widely studied. Tungsten carbide particles have high strength and hardness, good stability, low price, and can form a good metallurgical bond with the iron matrix. Tungsten carbide iron-based composites have the advantages of high plasticity and toughness of steel materials and high hardness and wear resistance of tungsten carbide, and the preparation process is simple. It has now become a hot issue in the field of wear-resistant materials.

[0003] Our country has rich rare earth and steel resources. Due to the relatively active properties of rare earth elements and relatively low electronegativity, they are more easily adsorbed at the grain boundaries between the matrix and the reinforcement, or react with the reinforcement to generate new substances with low interfacial energy, thereby reducing the interfacial energy, improving the wettability of the matrix and the reinforcement, purifying the grain boundaries, and improving the overall strength of the composite material.

[0004] Chinese invention patent CN108746636A discloses a tungsten carbide-steel-based composite material in which rare earth elements regulate the microscopic interfacial growth of particles. The rare earth elements are one or more, such as Nd, Ta, and Y, added in amounts of 2-5%. The material is ball-milled for 24-48 hours, then compressed using a tablet press and sintered in a vacuum tube furnace. This method, however, suffers from prolonged ball-milling and the lack of paraffin wax as a binder, resulting in poor adhesion of the rare earth elements to the tungsten carbide surface. Furthermore, the high amount of rare earth elements added and the lack of a concentration gradient prevent the reinforcing effects of the rare earth elements from being clearly evident, impacting the material's performance. Furthermore, the preparation process is lengthy, wasting manpower and resources.

[0005] This invention provides a method for preparing a rare earth element-doped WC particle-reinforced iron-based composite material with a concentration gradient. First, WC particles with high, medium, and low concentrations of rare earth elements are sequentially prepared, so that the rare earth elements are evenly coated on the tungsten carbide surface. The particles are then uniformly mixed with a matrix iron powder at a predetermined mass fraction. The resulting particles are then pressed into shape in a tablet press and finally sintered in a vacuum tube furnace to form the final sample. Summary of the Invention

[0006] To address the shortcomings of the aforementioned prior art, the present invention provides a method for preparing an iron-based composite material reinforced with tungsten carbide particles doped with concentration gradient rare earth elements. The method sequentially prepares tungsten carbide particles with high, medium, and low concentrations of rare earth dispersed and attached. The tungsten carbide particles, with surface-attached rare earth elements at a specific mass fraction, are then ball-milled with iron powder. The mixture is compacted using a tablet press and sintered in a vacuum tube furnace. By controlling the type, content, and concentration gradient of the rare earth elements, the wettability of the matrix and reinforcing particles can be improved, the density of the powder metallurgy sample can be increased, defects such as pores can be mitigated, and the wear resistance of the composite material can be enhanced to a certain extent.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A method for preparing a WC particle reinforced iron-based composite material doped with a concentration gradient rare earth element, wherein rare earth elements with different concentration gradients are used to perform gradient doping on a microscopic interface, comprising the following steps:

[0009] (1) Preparation of WC particles with high concentration of rare earth dispersion and attachment: WC particles and paraffin are heated in a water bath and slowly stirred to allow the paraffin to adhere to the WC surface. Then, rare earth elements with a mass fraction of 2.0%-4.0% and WC particles attached with paraffin are placed in a ball mill, and ethanol is added for ball milling for 2-4 hours.

[0010] (2) Preparation of WC particles with medium concentration of rare earth dispersion and attachment: The WC particles with 2.0%-4.0% rare earth elements and paraffin are heated in a water bath and slowly stirred to allow the paraffin to adhere to the surface. Then, the WC particles with a mass fraction of 1.5%-2.0% rare earth elements and paraffin attached are placed in a ball mill and ethanol is added for ball milling for 2-4 hours.

[0011] (3) Preparation of WC particles with low concentration of rare earth dispersion and attachment: The WC particles with 1.5%-2.0% rare earth element attachment and paraffin are heated in a water bath and slowly stirred to allow the paraffin to adhere to the surface. Then, the WC particles with a mass fraction of 1.0%-1.5% rare earth element and paraffin attachment are placed in a ball mill jar, and ethanol is added for ball milling for 2-4 hours.

[0012] (4) The mixture obtained in step (3) is taken out and placed in a vacuum drying oven to remove ethanol and paraffin.

[0013] (5) The rare earth-attached WC particles obtained in step (4) were ball-milled with pure iron powder for 1 h.

[0014] (6) The mixed powder obtained in step (5) is pressed into a preform, and placed in a vacuum tube furnace for sintering. The sintering temperature is set to 1350° C. and the holding time is 90 min.

[0015] As a preferred embodiment of the present invention, the rare earth powder added in step (1) is one of La, Ce, Y, Sc, and Nd, the tungsten carbide particles are spherical cast tungsten carbide of 60-80 mesh, and the iron powder is 60-100 mesh.

[0016] As a preferred embodiment of the present invention, in (1), (2) and (3), the ball milling process is as follows: during ball milling, first rotate forward for 60 minutes and then stop for 20 minutes, then reverse for 60 minutes and finally stop for 20 minutes, with a rotation speed of 300 r / min, and the above process is repeated 3 times.

[0017] As a preferred embodiment of the present invention, in (4), a vacuum drying oven is used for drying treatment, the vacuum degree is 6.0×10-1Pa, the drying temperature is 70°C, the time is 5 hours, the ethanol is removed, and the binder is removed at 200°C for 12 hours.

[0018] As a preferred embodiment of the present invention, the stainless steel grinding balls and powder in (5) are first rotated forward for 60-90 minutes, then stopped for 10 minutes, and then reversed for 60-90 minutes at 200 r / min.

[0019] As a preferred embodiment of the present invention, in said (6), the pressure is increased to 500 MPa and maintained for 3-5 minutes; then the pressure is released, and the pressure is increased to 600 MPa again and maintained for 8-10 minutes.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The present invention promotes the metallurgical bonding between tungsten carbide and iron by adding rare earth elements, regulates the interface of the composite material, and improves its mechanical properties.

[0022] (2) Compared with adding rare earth elements at one time, tungsten carbide particles with high, medium and low concentrations of rare earth dispersed and attached are prepared in sequence, and then the tungsten carbide particles with surface-attached rare earth with gradient concentration are mixed with iron powder by ball milling according to a certain mass fraction. This can give full play to the synergistic and coupling effects between rare earth elements and tungsten carbide particles. Compared with a non-gradient single concentration, by regulating three different concentrations and types of rare earth elements, three layers of rare earth element and WC mixtures with different concentration gradients are formed. The gradient structure material can give full play to the role of different characteristic sizes. These roles coordinate with each other and show their own mechanism of action, thereby improving and optimizing the overall performance of the material; thereby maximizing the mechanical properties of the composite material.

[0023] (3) Adding ethanol and paraffin wax will not affect the structure and properties of the material. The role of alcohol is to prevent agglomeration during the powder mixing process, and paraffin wax acts as a binder to firmly attach the rare earth elements to the WC surface. Both substances can be removed in a drying oven. The alcohol removal temperature is 60-70℃ for 5-6 hours, and the paraffin removal temperature is 200℃ for 9-10 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Micromorphology of undoped and rare earth La, Nd, Ce, and Y-doped WC particles reinforced with iron-based composites. (a) Undoped; (b) Nd concentration gradient doping; (c) Y concentration gradient doping; (d) La concentration gradient doping; and (e) Ce concentration gradient doping. DETAILED DESCRIPTION

[0025] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0026] Example 1

[0027] A method for preparing a concentration-gradient rare earth element-doped WC particle-reinforced iron-based composite material comprises the following steps:

[0028] (1) Preparation of WC particles with high concentration of rare earth dispersion and attachment: WC particles and paraffin are heated in a water bath and slowly stirred to allow the paraffin to adhere to the WC surface. Then, La element with a mass fraction of 2.0% and the WC particles attached with paraffin are placed in a ball mill, and ethanol is added for ball milling for 2 h.

[0029] Prepare WC particles with medium concentration rare earth dispersion and attachment: heat the above-mentioned 2.0% La element-attached WC particles and paraffin in a water bath, slowly stir to allow the paraffin to adhere to its surface, then put the WC particles with a mass fraction of 1.5% La element and paraffin-attached into a ball mill, and add ethanol for ball milling for 2 hours.

[0030] Prepare WC particles with low concentration of rare earth dispersion and attachment treatment, heat the above-mentioned 1.5% La element attached WC particles and paraffin in a water bath, slowly stir to make the paraffin adhere to its surface, then put the WC particles with a mass fraction of 1.0% La element and paraffin attached into a ball mill, and add ethanol for ball milling for 2 hours.

[0031] The ball milling process is as follows: first rotate forward for 60 minutes and then stop for 20 minutes, then reverse for 60 minutes and finally stop for 20 minutes, with a speed of 300r / min. The above process is repeated 3 times.

[0032] (2) The obtained mixture was taken out and placed in a vacuum drying oven to remove ethanol and paraffin.

[0033] (3) The obtained La-attached WC particles were ball-milled with pure iron powder for 1 h. When ball-milling, the stainless steel grinding balls and powder were first rotated forward for 60 min, then stopped for 10 min, and then reversed for 60 min at 200 r / min.

[0034] (4) The obtained mixed powder was pressed into a preform, and placed in a vacuum tube furnace for sintering. The sintering temperature was set to 1350°C and the holding time was 90 min.

[0035] Example 2

[0036] A method for preparing a concentration-gradient rare earth element-doped WC particle-reinforced iron-based composite material comprises the following steps:

[0037] (1) First, WC particles with high concentration of rare earth dispersed and attached were prepared. The WC particles and paraffin were heated in a water bath and slowly stirred to allow the paraffin to adhere to the WC surface. Then, Nd element with a mass fraction of 4.0% and the WC particles attached with paraffin were placed in a ball mill, and ethanol was added for ball milling for 4 h.

[0038] Then, WC particles with medium-concentration rare earth dispersion and attachment were prepared, the above-mentioned 4.0% Nd element-attached WC particles and paraffin were heated in a water bath, and slowly stirred to allow the paraffin to adhere to their surface. Then, the WC particles with a mass fraction of 2.0% Nd element and paraffin-attached were loaded into a ball mill, and ethanol was added for ball milling for 4 hours.

[0039] Secondly, WC particles with low concentration of rare earth dispersion and attachment were prepared, the above-mentioned 2.0% Nd element attached WC particles and paraffin were heated in a water bath, and slowly stirred to allow the paraffin to adhere to its surface, and then the WC particles with a mass fraction of 1.5% Nd element and paraffin attached were loaded into a ball mill, and ethanol was added for ball milling for 4 hours.

[0040] The ball milling process is as follows: first rotate forward for 60 minutes and then stop for 20 minutes, then reverse for 60 minutes and finally stop for 20 minutes, with a speed of 300r / min. The above process is repeated 3 times.

[0041] (2) The obtained mixture was taken out and placed in a vacuum drying oven to remove ethanol and paraffin.

[0042] (3) The obtained Nd-attached WC particles were ball-milled with pure iron powder for 2 h. The stainless steel grinding balls and powder were first rotated forward for 90 min, then stopped for 10 min, and then reversed for 90 min at 200 r / min.

[0043] (4) The obtained mixed powder was pressed into a preform, and placed in a vacuum tube furnace for sintering. The sintering temperature was set to 1350°C and the holding time was 90 min.

[0044] Example 3

[0045] A method for preparing a concentration-gradient rare earth element-doped WC particle-reinforced iron-based composite material comprises the following steps:

[0046] (1) First, WC particles with high concentration of rare earth dispersed and attached were prepared. The WC particles and paraffin were heated in a water bath and slowly stirred to allow the paraffin to adhere to the WC surface. Then, 2.0% Ce element by mass and the WC particles attached with paraffin were placed in a ball mill, and ethanol was added for ball milling for 3 h.

[0047] Then, WC particles with medium-concentration rare earth dispersion and attachment treatment were prepared, the above-mentioned 2.0% Ce element-attached WC particles and paraffin were heated in a water bath, and slowly stirred to allow the paraffin to adhere to their surface. Then, the WC particles with a mass fraction of 1.5% Ce element and paraffin-attached were loaded into a ball mill, and ethanol was added for ball milling for 3 hours.

[0048] Secondly, WC particles with low concentration of rare earth dispersion and attachment treatment were prepared, the above-mentioned 1.5% Ce element attached WC particles and paraffin were heated in a water bath, and slowly stirred to allow the paraffin to adhere to its surface. Then, the WC particles with a mass fraction of 1.0% Ce element and paraffin attached were loaded into a ball mill, and ethanol was added for ball milling for 3 hours.

[0049] The ball milling process is as follows: first rotate forward for 60 minutes and then stop for 20 minutes, then reverse for 60 minutes and finally stop for 20 minutes, with a speed of 300r / min. The above process is repeated 3 times.

[0050] (2) The obtained mixture was taken out and placed in a vacuum drying oven to remove ethanol and paraffin.

[0051] (3) The obtained Ce-attached WC particles were ball-milled with pure iron powder for 1 h. The stainless steel grinding balls and powder were first rotated forward for 80 min, then stopped for 10 min, and then reversed for 80 min at 200 r / min.

[0052] (4) The obtained mixed powder was pressed into a preform, and placed in a vacuum tube furnace for sintering. The sintering temperature was set to 1350°C and the holding time was 90 min.

[0053] Example 4

[0054] A method for preparing a concentration-gradient rare earth element-doped WC particle-reinforced iron-based composite material comprises the following steps:

[0055] (1) Preparation of WC particles with high concentration of rare earth dispersion and attachment: WC particles and paraffin are heated in a water bath and slowly stirred to allow the paraffin to adhere to the WC surface. Then, Y element with a mass fraction of 2.0% and the WC particles attached with paraffin are placed in a ball mill, and ethanol is added for ball milling for 2 h.

[0056] Prepare WC particles with medium concentration rare earth dispersion and attachment: heat the above-mentioned 2.0% Y element attached WC particles and paraffin in a water bath, slowly stir to allow the paraffin to adhere to its surface, then put the Y element with a mass fraction of 1.5% and the paraffin attached WC particles into a ball mill, and add ethanol for ball milling for 2 hours.

[0057] Prepare WC particles with low concentration of rare earth dispersion and attachment treatment, heat the above-mentioned 1.5% Y element attached WC particles and paraffin in a water bath, slowly stir to allow the paraffin to adhere to its surface, then put the Y element with a mass fraction of 1.0% and the WC particles attached with paraffin into a ball mill, and add ethanol for ball milling for 2 hours.

[0058] The ball milling process is as follows: first rotate forward for 60 minutes and then stop for 20 minutes, then reverse for 60 minutes and finally stop for 20 minutes, with a speed of 300r / min. The above process is repeated 3 times.

[0059] (2) The obtained mixture was taken out and placed in a vacuum drying oven to remove ethanol and paraffin.

[0060] (3) The Y-attached WC particles were ball-milled with pure iron powder for 1 h. The stainless steel grinding balls and powder were first rotated forward for 60 min, then stopped for 10 min, and then reversed for 60 min at 200 r / min.

[0061] (4) The obtained mixed powder was pressed into a preform, and placed in a vacuum tube furnace for sintering. The sintering temperature was set to 1350°C and the holding time was 90 min.

[0062] Comparative Example 1

[0063] A method for preparing a rare earth element-doped WC particle reinforced iron-based composite material comprises the following steps:

[0064] (1) First, WC particles with rare earth element dispersion and attachment were prepared. The WC particles and paraffin wax were heated in a water bath and slowly stirred to adhere the paraffin wax to the WC surface. Then, the WC particles with 1.0% La by mass and the paraffin wax-attached WC particles were placed in a ball mill and ball milled with ethanol for 2 h. The ball milling process was as follows: the ball mill was rotated forward for 60 min, then stopped for 20 min, then reversed for 60 min, and finally stopped for 20 min, at a speed of 300 rpm. This process was repeated three times.

[0065] (2) The obtained mixture was taken out and placed in a vacuum drying oven to remove ethanol and paraffin.

[0066] (3) The obtained La-attached WC particles were ball-milled with pure iron powder for 1 h.

[0067] (4) The obtained mixed powder was pressed into a preform, and placed in a vacuum tube furnace for sintering. The sintering temperature was set to 1350°C and the holding time was 90 min.

[0068] Comparative Example 2

[0069] A method for preparing a rare earth element-doped WC particle reinforced iron-based composite material comprises the following steps:

[0070] (1) First, WC particles with rare earth element dispersion and attachment were prepared. The WC particles and paraffin wax were heated in a water bath and slowly stirred to adhere the paraffin wax to the WC surface. Then, 1.0% Nd element by mass and the paraffin-attached WC particles were placed in a ball mill and ethanol was added for 4 hours. The ball milling process was as follows: the ball mill was rotated forward for 60 minutes, then stopped for 20 minutes, then reversed for 60 minutes, and finally stopped for 20 minutes, at a speed of 300 rpm. This process was repeated three times.

[0071] (2) The obtained mixture was taken out and placed in a vacuum drying oven to remove ethanol and paraffin.

[0072] (3) The obtained Nd-attached WC particles were ball-milled with pure iron powder for 1 h. When ball-milling, the stainless steel grinding balls and powder were first rotated forward for 60 min, then stopped for 10 min, and then reversed for 60 min at 200 r / min.

[0073] (4) The obtained mixed powder was pressed into a preform, and placed in a vacuum tube furnace for sintering. The sintering temperature was set to 1350°C and the holding time was 90 min.

[0074] Comparative Example 3

[0075] A method for preparing a rare earth element-doped WC particle reinforced iron-based composite material comprises the following steps:

[0076] (1) First, WC particles with rare earth element dispersion and attachment were prepared. The WC particles and paraffin wax were heated in a water bath and slowly stirred to adhere the paraffin wax to the WC surface. Then, 1.0% Ce (mass fraction) and the paraffin-attached WC particles were placed in a ball mill and ethanol was added for 3 h. The milling process was as follows: the mill was rotated forward for 60 min, then stopped for 20 min, then reversed for 60 min, and finally stopped for 20 min, at a speed of 300 rpm. This process was repeated three times.

[0077] (2) The obtained mixture was taken out and placed in a vacuum drying oven to remove ethanol and paraffin.

[0078] (3) The obtained Ce-attached WC particles were ball-milled with pure iron powder for 1 h. When ball-milling, the stainless steel grinding balls and powder were first rotated forward for 90 min, then stopped for 10 min, and then reversed for 60-90 min at 200 r / min.

[0079] (4) The obtained mixed powder was pressed into a preform, and placed in a vacuum tube furnace for sintering. The sintering temperature was set to 1350°C and the holding time was 90 min.

[0080] Comparative Example 4

[0081] A method for preparing a rare earth element-doped WC particle reinforced iron-based composite material comprises the following steps:

[0082] (1) First, WC particles with rare earth dispersed and attached were prepared. The WC particles and paraffin were heated in a water bath and slowly stirred to adhere the paraffin to the WC surface. Then, 1.0% Y element and the paraffin-attached WC particles were placed in a ball mill and ethanol was added for 3 hours. The ball milling process was as follows: the ball mill was rotated forward for 60 minutes, then stopped for 20 minutes, then reversed for 60 minutes, and finally stopped for 20 minutes. The speed was 300 rpm. This process was repeated three times.

[0083] (2) The obtained mixture was taken out and placed in a vacuum drying oven to remove ethanol and paraffin.

[0084] (3) The Y-attached WC particles were ball-milled with pure iron powder for 1 h. The stainless steel grinding balls and powder were first rotated forward for 90 min, then stopped for 10 min, and then reversed for 60-90 min at 200 r / min.

[0085] (4) The obtained mixed powder was pressed into a preform, and placed in a vacuum tube furnace for sintering. The sintering temperature was set to 1350°C and the holding time was 90 min.

[0086] According to the embodiment, a concentration gradient rare earth element doped WC particle reinforced iron-based composite material was prepared, and its performance test was described:

[0087] Table 1 Properties of the composite materials prepared in Examples 1-4 and Comparative Examples 1-4

[0088]

[0089] As can be seen from Table 1: Compared with the embodiment, the comparative example does not use the gradient concentration doping method of rare earth elements, and the obtained sample has lower hardness and compressive resistance, and the difference between the hardness of the interface reaction zone and the matrix hardness is higher than that of the embodiment; this is because the sample prepared by adding rare earth elements at one time does not have the ability to fully exert the effects of different characteristic sizes like the gradient structure material. These effects coordinate with each other and show their respective action mechanisms, thereby improving and optimizing the overall performance of the material.

[0090] The difference between the four embodiments is that different types of rare earth elements are used, but all use a method of preparing rare earth element-doped WC particles reinforced iron-based composite materials with a concentration gradient. The four comparative examples do not set a concentration gradient. Figure 1 The micromorphology of the undoped and rare earth La, Nd, Ce, Y-doped WC particles reinforced iron-based composite materials are shown respectively; Figure 1 It can be seen that the WC particles doped with rare earths are obviously better bonded to the iron matrix, and the separation interface is not so obvious. Among them, the WC particles doped with Ce have the best bonding with the iron matrix. From Figure e, it can be seen that the WC particles doped with Ce are completely bonded to the iron matrix, and the separation interface is almost invisible.

[0091] The present invention adopts a preparation method of WC particle reinforced iron-based composite materials doped with concentration gradient rare earth elements, and the performance of the prepared samples is significantly improved. The concentration gradient rare earth elements can give full play to the synergistic and coupling effects between the rare earth elements and tungsten carbide particles, refine the grains, purify the grain boundaries, and significantly improve the hardness and tensile strength.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a concentration-gradient rare earth element-doped WC particle-reinforced iron-based composite material, characterized by: Gradual doping of the microscopic interface with rare earth elements of different concentration gradients includes the following steps: (1) Preparation of WC particles with high concentration of rare earth dispersion and attachment: Heat the WC particles and paraffin in a water bath and slowly stir to allow the paraffin to adhere to the WC surface. Then, place the WC particles with a mass fraction of 2.0%-4.0% of rare earth elements and paraffin-attached WC particles into a ball mill and add ethanol for ball milling for 2-4 hours. (2) Preparation of WC particles with medium concentration of rare earth dispersion and attachment: Heat the WC particles with 2.0%-4.0% rare earth elements and paraffin wax in a water bath and slowly stir to allow the paraffin wax to adhere to the surface. Then, place the WC particles with 1.5%-2.0% rare earth elements and paraffin wax attached into a ball mill and add ethanol for ball milling for 2-4 h. (3) Preparation of WC particles with low concentration of rare earth dispersion and attachment: The WC particles with 1.5%-2.0% rare earth elements and paraffin wax are heated in a water bath and slowly stirred to allow the paraffin wax to adhere to the surface. Then, the WC particles with 1.0%-1.5% mass fraction of rare earth elements and paraffin wax are placed in a ball mill and ethanol is added for ball milling for 2-4 h. (4) taking out the mixture obtained in step (3) and placing it in a vacuum drying oven to remove ethanol and paraffin; (5) ball milling the rare earth-attached WC particles obtained in step (4) with pure iron powder for 1 h; (6) The mixed powder obtained in step (5) was pressed into a preform, and placed in a vacuum tube furnace for sintering. The sintering temperature was set to 1350°C and the holding time was set to 90 minutes.

2. The method for preparing the concentration-gradient rare earth element-doped WC particle-reinforced iron-based composite material according to claim 1, characterized in that: The rare earth powder added in step (1) is one of La, Ce, Y, Sc, and Nd.

3. The method for preparing the concentration-gradient rare earth element-doped WC particle-reinforced iron-based composite material according to claim 1, characterized in that: In the steps (1), (2) and (3), the ball milling process is as follows: first, the ball mill rotates forward for 60 minutes, then stops for 20 minutes, then reverses for 60 minutes and finally stops for 20 minutes, with a rotation speed of 300 r / min, and the above process is repeated 3 times.

4. The method for preparing the concentration-gradient rare earth element-doped WC particle-reinforced iron-based composite material according to claim 1, characterized in that: In step (5), the stainless steel grinding balls and powder are first rotated forward for 60-90 minutes, then stopped for 10 minutes, and then reversed for 60-90 minutes at 200 r / min.

5. The method for preparing the concentration gradient rare earth element doped WC particles reinforced iron-based composite material according to claim 1, characterized in that: The conditions for pressing the preform in step (6) are as follows: increasing the pressure to 500 MPa and maintaining the pressure for 3-5 minutes; then releasing the pressure, increasing the pressure again to 600 MPa and maintaining the pressure for 8-10 minutes.

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